Having a little engine noise, and planning major engine work deviating from OEM specs to solve it?
One would suggest that you reconsider.
Take it to a reputable independent GM/Chevrolet engine mechanic for a look. He ought to be able to give you practical professional advice.
The AFM system is a POS. Well known for having issues.
That AFM is a known problem with those engines. He’s on the right track and if it’s not addressed soon he will lose that engine.
My 2001 Chevy had the lifter tick fairly soon iirc. The mechanic said it wasn’t that big of a deal. Hit a deer at 160,000 miles and totaled the truck. Got rid of the tick.
For the active fuel management they say that the ticking is caused by poor lubrication when the 4 cylinders get shut down and something wears out on those 4 cylinders.